Variable-speed controller.



C. T. HENDERSON.

VARIABLE SPEED CONTROLLER.

APPLICATION FILED JULY 29. I913.

1,233,877. Patented July 17,1917.

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VARIABLE SPEED CONTROLLER.

APPLICATION FILED JULY 29. I913.

Patented July 17,1917.

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CLARK T. HENDERSON, 0F MILWAUKEE, WISCONSIN, ASSIGNOR TO THE CUTLER-HAMMER MFG. 00., OF MILWAUKEE, WISCONSIN, A. CORPORATION OF WISCONSIN.

VARIABLE-SPEED CONTROLLER.

Specification of Letters Patent.

Application filed July 29, 1913. Serial No. 781,725.

To all whom it may concern Be it known that I, CLARK T. HENDERSON, acitizen of the United States, residing at Milwaukee, in the county ofMilwaukee and State of Wisconsin, have invented new and usefulImprovements in Variable-Speed Controllers, of which the following is afull, clear,'concise, and exact description, reference being had to theaccompanying drawing, forming a part of this specification.

This invention relates to variable speed controllers.

The invention is particularly applicable to the control of variablespeed electric motors employed to drive variable speed mechanisms.generally provided with mechanical or other gearing, by means of whichvarious speeds may be obtained. There are, however, undesirablelimitations upon the use of gearing alone to effect speed changes. Thusthe range of speed is limited since each set of gears causes themechanism to be driven at a definite speed ratio with respect to thespeed of the drivingmeans. Also the transition from one speed to thenext is generally so abrupt as to be objectionable. By employing avariable speed electric motor as the driving means, however, a widerange of speedmay be obtained and the transition from one set'of gearingto another may be made as gradual as desired.

In order to obtain a gradual change of speed over a wide range it 1snecessary to vary the motor speed whenever a change is made from one setof gearing to another and also to vary the motor speed while themechanism is being driven through each set. of gears.

Furthermore, when a change is made from a low speed drive to a higherspeed, the load on the motor will be proportionately'increased so thatitbecomes necessary to provide means for preventing an abnormal inrush ofcurrent to themotor and also to hold down the voltage at the motorterminals to allow sufiicient latitude for increasing the voltage toeffect speed changes in the motor.

Heretofore it has been proposed to employ a single resi'stanceforcontrolling the motor. This has necessitated rei-nserting the resistancein circuit at each change in gearing, thereby greatly complicating the 5motor controller.

Variable speed mechanisms are.

An object of this invention is to simplify the controller for thevariable speed electric trated as employed in connection with animproved variable speed mechanism employing two sets of'gears.

While the controller is particularly adapted for use in connection withthe variable speed mechanism illustrated, it is, of course, apparentthat it is in no wise limited to such use, as it may be made in variousforms for use with different mechanisms. Accordingly the invention isonly diagrammatically illustrated so that in practice it may be embodiedin the form best suited to the conditions.

In the accompanying drawings Figure 1 illustrates diagrammatically oneform of the improved controller.

Fig. 2 illustrates diagrammatically a modified arrangement thereof.

Fig. 3 is a plan view, partially in section, of the variable speedmechanism disclosed in my prior application.

Fig. 4:- is a section on the line AB of Fig. 3.

Fig. 3 illustrates an electric motor 1 provided with an armature shaft2. Power is transmitted through various gears to drive clutch isprovided with an armature member 6 fixed to the shaft and a magnetmember 7 freely rotatable thereon. A pinion 8 is fixed to the magnetmember of the clutch.

.The mechanical clutch has an inner member 9 loose on the shaft 3 and anouter member 10 fixed to the shaft. A gear 11 is fixed to the innermember. of the mechanical clutch. The mechanical clutch is preferably aone-wayball or roller clutch. The inner member of the clutch is providedwith radial projections 12, between which are recesses 13 havinginclined bottoms 14. Balls or'rollers 15 are arranged in these recessesbetween the inner and outer clutch members. Upon rotation of the innermember in the direction indicated by the arrow, Fig. 4, the rollerswill, crowd to thenarrow ends of the recesses until they wedge betweenthe outer and inner clutch members, thus caus-.

s It is apparent, therefore, that if the magnetic clutch is deenergized,a low speed drive will be eflected from the motor shaft through thepinion 18, gear 17, counter shaft 16, pinion 19, gear 11, and themechanical clutch to the driven shaft 3. The magnet member of themagnetic clutch will also rotate, but inefi'ectively since the magneticclutch isdeenergized. Upon energization of the magnetic clutch a'highspeed drive will be effected through gear 17, pinion 8 and the magneticclutch. This will cause disengagement of the mechanical clutch memberssince the outer member will be driven at a higher speed than the innermember. I

By making the ratios of pinion18 to gear 17 one to three, gear 17 topinion 8 three to one, and pinion 19 to gear 11 one to three, a lowspeed driving ratio of one to nine may be obtained, or a high speedratio of one to one. These ratios are merely illustrative and may bevaried as desired. I

Fig. 1, illustrates diagrammatically the preferred form of controller.The electric motor is illustrated as provided with an armature 20 anda'shunt field 21. A shunt moo magnetic clutch issupplied from suitable vments 29 and 30 for purposes hereinafter described. The segment 29 hasan auxiliary tor has been selected merely because it is well adaptedforthis type of service and may be readily controlled, although any.suitable motor may, of course, be employed. Ourrentfor the motor andfor energizing the mains through the main switch 22. Control of themotor is preferably obtained by means of resistance in the armaturecircuit. This resistance comprises the section 23 provided with contacts24 and the section .25

connected to the section 23 by contact 26 and provided'with contacts 27.A pivoted controller arm 28, electrically connected to the positive mam,1s adapted to successively contact -with the 'contacts 24, 26 and 27.The

arm 28 is also adapted to contact "with segcontact 31 inad'vance of'thesegment and connected thereto by a resistance 32.

The motor circuit is controlled by an electro-magnetic switch 33operated by a coil 34 connected between the segment 29 and the negativemain. When the coil-is energized the switch bridges contacts in themotor armature circuit to start the motor, and

The magnetic clutch has its magnet coil 36 connected between the segment30 and the negative main. An automatic rheostat is provided in theclutch circuit whereby the strength of current may be graduallyincreased to cause the clutch to gradually pick up the load. Thisautomatic rheostat comprises a resistance 37 provided with contacts 38and an arm 39 adapted to engage these contacts in succession. The arm 39is operated by a coil 40 connected in a shunt around the clutch magnet.Upon closure of the clutch circuit by the controller arm 28 the rheostatarm will move, retarded by the ,dashpot 41, to gradually cut theresistance 37 out of the clutch circuit. As the last step of resistance37 is 'cut-out,.the arm 39 engages a contact 42 which controls a circuitfor a solenoid 43 for releasing a latch 44 which cooperates with aprojection 45 on the controller arm for a purpose hereinafter described.v

The operation of the controller will now be described. As illustrated,all the circuits are open and the motor is at rest. Upon moving thecontact arm 28 to the right into engagement with contact 31, the switchsolenoid 34 will be energized by the circuit from the positive mainthrough conductor 46, controller arm 28, contact 31, conductor 47, andswitches 35 to the negative main. This will close the motor switch andarmature current will flow from the positive lead through both sectionsof the resistance in series to start the motor- Under these conditionsthe variable speed mechanism Will be driven through the low speed gearand variations in speed may be obtained by moving the controller ,armback and forth over the contacts 24. When the controller arm engages thesegment '29, the resistance 32 is inserted in the circuit of. the motorswitch solenoid to reduce the current therein to an amount simplysufficient to maintain the switch closed. When the arm has been movedinto engagement with the contact 26, the maximum speed with the lowgearing is obtained since all the 'low speed resistance section 23 hasbeen cut out of the motor circuit. In this position the controller armengages the segment 30,-thus energizing the magnetic clutch through theresistance 37.

The latch 44, which, normally occupies the a circuit will be closedthrough the latch.

coil from the controller arm, through segment 30, conductor 48, arm 39,contact 42, conductor 19,- coil 43 and conductor 50 to .the negativemain. The latch will immediately be drawn to the dotted line positionillustrated and the controller arm may then be moved back and forth overresistance to vary the motor speed during the operation of the mechanismby the high speed gearing.

Fig. 2 illustrates a modified arrangement of the controller circuits. Inthis modification, a resistance 51, provided with contacts 52, isconnected to the segment in position to be engaged by the controller armbefore the arm engages the segment. With this arrangement the automaticrheostat in the clutch circuit and the latch 44 may be dispensed with.It will be readily understood from the drawing that as the controllerarm engages the contact 52, the clutch circuit will be completed throughthe resistance 51. Further movement of the arm will increase theeffectiveness of the clutch by cutting out successive steps ofresistance from the clutch circuit. The relative arrangement of contactsis referably. such that the controller arm oes not come into contactwith the first contact 27 ofmotor resistance 25 until the magneticclutch has reached its maximum energization.

It is apparent that this invention provides a simple controller forvariable speed mechanisms which, by a single movement of a controllerarm in one direction, will start the driving motor, cause the motor toaccelerate to its maximum speed with one set of gearing in operation,automatically cause the motor to drive through the next set of gearing,and, thereafter, cause acceleration of the motor to its maximum speedwith this set of gearing. At the same time sufficient resistance isalways provided to properly protect the motor as the load varies withchanges in the driving gear ratio.

lVhat I claim as new and desire to secure Letters Patent of the UnitedStates is: 1. In combination, a driven shaft, a variable speed drivingmotor therefor, means for varying the driving ratio between said motorand shaft, and means for controlling bination, a driven shaft, a drivingmotor therefor, a plurality of sets of gears for connecting said motorand said shaft for different speed ratios, power operated means foreffecting substitution of one of said sets of gears for another, acontroller for varying the speed of said motor through a predeterminedrange and means associated with said controller for effecting a gradualtransition from one of said speed ratios to another through the mediumof said power operated means at an intermediate and substantiallyconstant speed of said motor.

3. In a variable speed mechanism, a va riable speed driving motor, aplurality of sets of driving gears between said motor and the drivenmechanism, a resistance divided into sections corresponding in number tothe sets of driving gears, a controller arm movable over said resistancesections, in succession, to vary the same, and means controlled by saidarm for bringing into operation the set of gears corresponding to thesection of resistance over which said con troller arm is being moved.

4. In a variable speed mechanism, in combination, a driven shaft, adriving motor therefor, a plurality of sets of gears for connecting saidmotor and said shaft for different speed ratios, electromagnetic meansfor effecting substitution of one of said sets of gears for another, avariable resistance for controlling the speed of said motor through apredetermined range, controlling means for said resistance and meansassociated with said controlling means for energizing saidelectromagnetic means and for varying the action thereof to effect agradual transition from one speed ratio to another at an intermediateand substantially con stant speed of said motor. 7 v 5. In a variablespeed mechanism, a variable speed driving motor, a plurality ofdrivingconnection's between said motor and sition, also controlling saidmagnetic clutch,

means for causing said clutch, when energized, to gradually becomeeffective, and

means for insuring a maximum efliciency in said clutch beforesaidresistance may be further varied to acceleratesaid motor.

6. In a variable speed mechanism, a 'variable speed driving motor,electro-Inagnetic means forvarying the driving connections for causingsaid electro-magnetic means, when energized, to gradually becomeefficient, a variable resistance for controlling said motor, acontroller arm adapted to move over said resistance to vary the same,said arm, at an intermediate point in its movebetween said motor andmechanism, means mechanism, a resistance for controlling said 10' motorwhile said low speed connection is in operation, a controller arm forvarying said resistance, a high speed driving connection between saidmotor and mechanism, said connection including a magnetic clutch, meansfor causing said clutch, when energized, to gradually increase inefiiciency to insure a gradual transition from low to high speed, and 'aresistance for controlling said motor while said high speed connectionis in operation, said controller arm also serving to ,control saidmagnetic clutch and said high speed resistance by successive movementsin the same direction.

8. In a variable speed mechanism, in combination, a driven shaft, adriving motor therefor, a plurality of sets of gears for connecting saidmotor and said shaft for different speed ratios, an electromagneticclutch for effecting substitution of one of said sets of gears r anotherand controlling means for said motor and said clutch including twovariable resistances, one for varying the speed of said motor through apredetermined range and the other for vary:

ing the action of said clutch, said latter resistance functioning toeffect a gradual transition from one speed ratio to another through saidclutch at an intermediate speed of said motor.

9. In combination, a variable speed mechanism, a variable speed drivi nmotor therefor, a motor switch, a control ing resistance for varying thespeed of said motor, means for changing the driving ratio between saidmotor and mechanism, said means including a magnetic clutch, aresistance for controlling the energization of said clutch, and acontroller arm movable through successive steps in the same direction toclose, said switch, vary said motor resistance and control said magneticclutch and its aforesaid resistance.

.10. In combination, a variable speed mechanism, a variable speeddriving motor therefor, a controlling resistance for said motor, drivingmeans between said motor and mechanism, said means including a magneticclutch, a coil for said clutch, an automatic rheostat for controllingthe energization of said 0011, a controller arm for varying saidresistance and controlling the circuit of said coil and rheostat, meanscooperating with said arm for holding it in an intermediate position,and means controlled by said automatic rheostat for releasing saidholdingmeans.

11. In combination, a mechanism to be driven, a variable speed drivingmotor therefor, driving connections .including a magnetic clutch betweensaid motor and mechanism, a coil for said'clutch, a resistance in serieswith said coil, a controlling resistance for said motor, and controllingmeans gov- .driving motor therefor, operative connections between saidmotor and said member including means for varying the driving ratio, anda common controller for said motor and said ratio changing meansoperable to efiect operation of said meansafter partial acceleration ofsaid motor and thereafter further accelerate said motor.

13. In combination, a driven member, a driving motor therefor, operativeconnections between said motor and said member including means forvarying the driving ratio, and a common controller for said motor andsaid ratio changing means including a resistance for the motor, saidcontroller being operable to remove a limited portion of said resistancefrom circuit, effect operation of said means and remove the remainder ofsaid resistance from circuit progressively.

' 14. In combination, a driven member, a

"driving motor therefor,- operative connections between said motor andsaid member, electromagnetic means controlling said connections to varythe driving ratio, a resistance for the motor and controlling means forsaid resistance adapted to energize said electromagnetic means uponremoval of a limited part of said resistance from circuit and tothereafter remove the remainder of said resistance from circuit.

In witness whereof, I have hereunto subscribed my name in the presenceof two witnesses.

CLARK T. HENDERSON.

Witnesses:

r F. H. HUBBARD,

J. F. WATSON.

